List of Excipients in Branded Drug GRISEOFULVIN MICROSIZE

Generic Drugs Containing GRISEOFULVIN MICROSIZE

Company	Ingredient	NDC	Excipient
Heritage Pharmaceuticals Inc d/b/a Avet Pharmaceuticals Inc	griseofulvin	23155-865	MAGNESIUM STEARATE
Heritage Pharmaceuticals Inc d/b/a Avet Pharmaceuticals Inc	griseofulvin	23155-865	POLOXAMER 188
Heritage Pharmaceuticals Inc d/b/a Avet Pharmaceuticals Inc	griseofulvin	23155-865	SILICON DIOXIDE

What are the Most Frequently-Used Excipients in GRISEOFULVIN MICROSIZE?

# Of NDCs	Excipient
2	MAGNESIUM STEARATE
2	POLOXAMER 188
2	SILICON DIOXIDE

Griseofulvin Microsize Excipient Strategy, Formulation Patents, and Commercial Opportunities

Last updated: September 24, 2026

Griseofulvin microsize is an established oral antifungal with limited molecule-level exclusivity and a largely generic commercial structure. The principal opportunity is formulation differentiation: improving wetting, dose uniformity, palatability, pediatric usability, food-effect control, and supply-chain economics without changing the active ingredient or therapeutic indication.

The strongest development paths are an alcohol-free oral suspension, a taste-masked pediatric product, a rapidly dispersible tablet, and a lipid-enabled formulation designed to reduce variability in absorption. Any new product must preserve the pharmacokinetic and clinical performance associated with microsized griseofulvin while avoiding confusion with ultramicrosize griseofulvin products.

What is griseofulvin microsize and how does it differ from ultramicrosize griseofulvin?

Griseofulvin microsize is a poorly water-soluble antifungal administered orally for dermatophyte infections of the skin, hair and nails. Its absorption improves when taken with a fatty meal. Microsizing reduces particle size and increases effective surface area, improving dissolution compared with conventional griseofulvin powder.

Ultramicrosize griseofulvin, marketed historically under products such as Gris-PEG, uses smaller particles and lower labeled doses than microsize products. The two forms should not be treated as interchangeable on a milligram-for-milligram basis.

Attribute	Griseofulvin microsize	Griseofulvin ultramicrosize
Typical adult tablet strength	250 mg	125 mg
Common pediatric dosing framework	Weight-based, product-specific	Weight-based, product-specific
Key performance issue	Dissolution and food-dependent absorption	Higher apparent bioavailability from smaller particles
Main formulation challenge	Wetting, dispersion, taste and dose uniformity	Dose precision and maintaining ultrafine particle size
Commercial status	Generic oral products	Separate formulation category
Substitution	Not automatically interchangeable	Not automatically interchangeable

DailyMed labeling for microsize products identifies 125 mg and 250 mg oral tablets and instructs administration with fatty food to improve absorption.[1] Product-specific labeling controls dosing, administration and substitution decisions.

What excipients are used in griseofulvin microsize tablets?

The excipient system depends on the manufacturer, strength, manufacturing process and dosage form. Typical tablet functions include fillers, binders, disintegrants, lubricants, glidants, coating agents and colorants.

Common excipient classes for a conventional griseofulvin microsize tablet include:

Formulation function	Candidate excipient classes	Development purpose
Diluent	Lactose, microcrystalline cellulose, dibasic calcium phosphate, mannitol	Tablet mass and manufacturability
Binder	Povidone, copovidone, pregelatinized starch, hydroxypropyl cellulose	Granule and tablet strength
Disintegrant	Croscarmellose sodium, crospovidone, sodium starch glycolate	Tablet breakup and dispersion
Lubricant	Magnesium stearate, sodium stearyl fumarate	Ejection and tooling protection
Glidant	Colloidal silicon dioxide, talc	Powder flow
Film coating	Hypromellose, polyvinyl alcohol, polyethylene glycol, titanium dioxide	Appearance, protection and swallowability
Sweetener or flavor	Sucralose, saccharin sodium, flavors	Primarily relevant to suspensions and chewables
Suspending agent	Xanthan gum, sodium carboxymethylcellulose, hypromellose	Physical stability in liquid products
Wetting agent	Polysorbates, poloxamers, sodium lauryl sulfate	Surface wetting and dispersion
Vehicle	Purified water, glycerol, sorbitol solution, polyethylene glycol	Liquid dosage-form delivery

An excipient cannot be selected solely on the basis of dissolution enhancement. Griseofulvin has a low aqueous solubility profile, and wetting agents can improve apparent dissolution while also creating foaming, precipitation, taste and stability problems.

A development program should screen excipient systems against:

1. Particle-size distribution and agglomeration.
2. Dissolution in biorelevant media.
3. Tablet disintegration and friability.
4. Content uniformity at pediatric dose levels.
5. Chemical and physical stability.
6. Food-effect sensitivity.
7. Taste and mouthfeel.
8. Excipient tolerability in children.
9. Manufacturing compatibility and supply risk.

What formulation strategy offers the best commercial opportunity?

The strongest opportunity is a pediatric oral liquid that improves administration without requiring patients to consume a fatty meal. Existing microsize products are primarily solid oral dosage forms, while dermatophyte infections frequently require prolonged treatment and can affect children.

Pediatric oral suspension

A microsize suspension could address several practical problems:

• Difficulty swallowing tablets.
• Dose adjustment by body weight.
• Administration to younger children.
• Improved adherence during prolonged therapy.
• Potential differentiation from basic generic tablets.

The core technical challenge is maintaining uniform drug distribution. A suspension must resist rapid sedimentation, redisperse with modest shaking and deliver consistent doses across the labeled shelf life.

Candidate approaches include:

• Wet-milled or controlled-milled griseofulvin particles.
• Structured vehicles using xanthan gum or cellulose polymers.
• A wetting-agent and surfactant system.
• Taste masking with polymer coating or ion-pairing approaches.
• Unit-dose sachets or oral syringes for dose accuracy.
• Alcohol-free and sugar-reduced vehicles.

A liquid product with high solids loading may create sedimentation and mouthfeel problems. A lower-strength suspension may improve dosing flexibility but increase administration volume.

Chewable or orally disintegrating tablet

A chewable tablet could provide a lower-cost alternative to a liquid. Its formulation must manage griseofulvin’s bitter taste and avoid excessive tablet mass.

Relevant excipient approaches include:

• Mannitol for cooling mouthfeel.
• Crospovidone for rapid breakup.
• Microencapsulated griseofulvin for taste masking.
• Flavor and high-intensity sweetener systems.
• Direct-compression excipients with low moisture sensitivity.

A chewable product may be commercially attractive if it can demonstrate adequate dissolution without relying on a fatty meal. The product would still require careful clinical and regulatory assessment because improved in vitro dissolution does not automatically establish equivalent systemic exposure.

Lipid-enabled formulation

A lipid-based formulation could address the established food effect. Candidate systems include self-emulsifying or self-microemulsifying delivery systems, lipid suspensions and solid lipid dispersions.

The development objective would be to reduce the difference between fed and fasted exposure. The principal risks are:

• Variable excipient digestion.
• Capsule fill or liquid-fill manufacturing complexity.
• Physical instability.
• Drug precipitation after dispersion.
• Higher cost than a conventional tablet.
• Regulatory scrutiny of bioequivalence and food-effect claims.

This route has the highest technical differentiation but also the highest development and manufacturing burden.

What patents could protect a new griseofulvin microsize product?

New patent protection would likely attach to the formulation, manufacturing process, particle engineering, dosing system or specific therapeutic use rather than to griseofulvin itself.

Potential claim categories include:

Claim category	Protectable subject matter	Commercial value
Composition	Defined griseofulvin particle size, excipient ratios or solid dispersion	Protects the product architecture
Particle engineering	Milling process, particle-size distribution, morphology or agglomerate control	Can create manufacturing barriers
Suspension	Sedimentation profile, redispersibility, viscosity and dose uniformity	Protects pediatric liquid performance
Taste masking	Coating, matrix, encapsulation or flavor system	Supports pediatric differentiation
Bioavailability	Reduced food effect or improved exposure under defined conditions	Potentially valuable but evidence-intensive
Dosage regimen	Weight-based dosing or administration schedule	Narrower protection and possible obviousness risk
Packaging	Unit-dose system, oral syringe or reconstitution configuration	Supports product differentiation
Manufacturing	Continuous milling, granulation or coating process	Can be difficult to design around if process-specific

A commercially meaningful patent portfolio would normally combine composition claims with manufacturing and performance claims. A single broad claim directed to "griseofulvin with excipients" would face substantial prior-art and obviousness risk because the active ingredient and conventional oral formulations are longstanding.

Patent applicants should define measurable technical parameters, such as:

• D10, D50 and D90 particle-size limits.
• Specific surface area.
• Dissolution at defined pH and agitation conditions.
• Sedimentation volume and redispersion time.
• Assay uniformity across container withdrawals.
• Fed/fasted exposure ratios.
• Long-term stability after opening.
• Taste-mask retention after storage.

When does griseofulvin microsize lose exclusivity?

Griseofulvin microsize has long lost original compound and basic oral-product exclusivity. The current market is primarily generic, and commercial protection depends on manufacturing capability, regulatory approvals, customer contracts and formulation differentiation.

The main exclusivity categories are:

Exclusivity type	Current commercial relevance
Original active-ingredient patent	Expired
Original conventional tablet protection	Expired or commercially exhausted
New formulation patent	Available only for genuinely novel and non-obvious subject matter
Orphan exclusivity	Not generally associated with standard griseofulvin microsize products
Pediatric exclusivity	Product-specific and not assumed
Regulatory exclusivity for a new generic	Generally limited compared with a new chemical entity
Trade secret protection	Relevant to particle engineering, coating and process controls

A new 505(b)(2) product could pursue a differentiated formulation pathway if it relies partly on published literature or an FDA finding concerning griseofulvin while introducing a material change in dosage form or performance. A conventional abbreviated new drug application would generally be more appropriate for a standard equivalent tablet, subject to FDA product-specific requirements.

What is the FDA and Orange Book status of griseofulvin microsize?

FDA-listed griseofulvin products include microsize oral tablets and separate ultramicrosize products. DailyMed labeling identifies griseofulvin microsize tablets for oral administration and lists the relevant inactive ingredients for individual manufacturers.[1]

The Orange Book should be reviewed by product and application number because listings can change as approvals are withdrawn, products are discontinued or new generic applications are approved.[2] The practical market conclusion is that standard microsize tablets have no meaningful branded exclusivity barrier comparable with a recently launched small-molecule product.

For a new formulation, the regulatory route depends on the degree of change:

• An ANDA is suited to a product matching a reference listed drug in dosage form, strength, route and relevant performance characteristics.
• A 505(b)(2) application may be appropriate for a materially different liquid, lipid-based or modified delivery product.
• A new drug application may be required when the proposed product cannot rely sufficiently on an existing reference or published evidence.

The excipient system must comply with FDA expectations for safety, quality, compatibility and manufacturing control. Novel excipients or unusual levels of established excipients can increase regulatory burden.

Which companies are challenging griseofulvin microsize?

The competitive field is fragmented. Generic manufacturers and contract manufacturers can compete on:

• 125 mg and 250 mg tablet availability.
• Wholesale acquisition cost.
• Medicaid and managed-care contracts.
• Supply reliability.
• Bottle sizes and packaging.
• Retail pharmacy distribution.
• Authorized generic relationships.

The primary competitive threat is substitution among generic microsize tablets, not a large branded innovator campaign. A differentiated entrant would compete against both low-cost tablets and alternative antifungal therapies, including terbinafine, itraconazole and fluconazole, depending on infection type and prescriber preference.

A new product must therefore create value beyond the active ingredient. Possible value propositions include:

• Pediatric dosing accuracy.
• Improved taste.
• Lower administration burden.
• Reliable exposure without a high-fat meal.
• Lower tablet burden.
• Easier pharmacy dispensing.
• Better adherence during prolonged treatment.

What generic entry risks exist for a new griseofulvin microsize formulation?

The principal generic-entry risk depends on the patent claims and the FDA pathway.

Risks for a conventional tablet

A conventional tablet is exposed to rapid generic competition because:

• The active ingredient is old.
• Conventional excipients are widely known.
• Tablet manufacturing is routine.
• Bioequivalence pathways are familiar.
• Switching costs for pharmacies are low.

A tablet sponsor would need a cost or supply advantage rather than relying on broad formulation patents.

Risks for a pediatric suspension

A suspension may have stronger practical protection if it depends on a narrow combination of particle engineering, taste masking and physical-stability parameters. Even so, a competitor could design around a polymer, surfactant or viscosity range unless claims are tied to a demonstrated performance profile.

Paragraph IV challenges

A patent-listed formulation could face an ANDA applicant’s Paragraph IV certification asserting that the patent is invalid, unenforceable or not infringed. The commercial effect depends on:

• Whether the patent is listed for the relevant product.
• Whether the claims cover the generic’s formulation.
• The timing of the notice letter.
• Whether litigation is filed within the statutory period.
• Whether a 30-month stay applies.
• Whether the challenger receives first-filer status.

For an old active ingredient, the greater Paragraph IV risk usually falls on newly patented formulation claims, not on the griseofulvin molecule itself.

What manufacturing and IP barriers matter most?

The most defensible technical barriers are process-linked. These include controlled wet milling, narrow particle-size distribution, uniform coating of hydrophobic particles, suspension redispersibility and robust taste masking.

Manufacturing controls should address:

• Milling energy and temperature.
• Residual solvent, if used in coating.
• Particle agglomeration during drying.
• Blend segregation.
• Lubricant sensitivity.
• Scale-up effects on dissolution.
• Microbial control for aqueous liquids.
• Container-closure compatibility.
• Dose delivery from oral syringes or measuring devices.

Trade secrets may be more durable than patents for milling parameters, coating conditions and order-of-addition controls. Patent protection remains important when the commercial value depends on a measurable formulation profile that competitors can identify through reverse engineering.

How does griseofulvin microsize compare with competing antifungals?

Product class	Main advantage	Main limitation	Excipient opportunity
Griseofulvin microsize	Established dermatophyte treatment and pediatric clinical use	Food-dependent absorption and prolonged therapy	Suspension, taste masking and food-effect reduction
Terbinafine	Shorter treatment for selected infections	Age, indication and safety considerations	Pediatric granules or improved dispersibility
Itraconazole	Broader antifungal activity	Variable absorption and drug interactions	Solution and lipid-system optimization
Fluconazole	Convenient dosing and broad use	Different spectrum and indication profile	Palatable liquid and pediatric dosing
Topical antifungals	Low systemic exposure	Limited utility for hair and nail involvement	Film-forming and adherence-enhancing systems

Griseofulvin’s commercial niche is strongest where an oral dermatophyte treatment is needed and pediatric administration, clinical familiarity or cost matters.

What are the most attractive commercial opportunities?

The best near-term opportunity is a differentiated pediatric microsize suspension with an alcohol-free vehicle, accurate dosing and documented taste improvement. A second opportunity is a chewable product for children who cannot reliably swallow tablets.

A lipid-enabled product may command stronger differentiation, but it requires more development capital and carries greater regulatory risk. Its value depends on proving reduced food effect or improved exposure, not merely showing higher dissolution.

Revenue exposure should be modeled from treated patient volume, duration of therapy, product-specific net price and channel mix. Public financial disclosures generally do not isolate griseofulvin microsize revenue because the product is sold within broader generic portfolios. A commercial model should therefore use scenario ranges rather than attribute corporate revenue directly to this molecule.

Key Takeaways

• Griseofulvin microsize is a mature generic product with no meaningful original-molecule exclusivity.
• The main opportunity is formulation differentiation, especially for pediatric use.
• An alcohol-free, taste-masked oral suspension has the clearest unmet commercial need.
• A chewable tablet can offer lower manufacturing complexity than a liquid.
• Lipid-based delivery has higher technical differentiation but greater regulatory and manufacturing risk.
• New patents should focus on particle engineering, performance-defined compositions, taste masking, suspension stability and food-effect reduction.
• Conventional tablets face rapid generic substitution and weak patent barriers.
• Manufacturing know-how may provide stronger protection than broad excipient claims.
• Orange Book and DailyMed records must be reviewed at the product and application level because manufacturer listings can change.
• A 505(b)(2) strategy may be more suitable than an ANDA for a materially differentiated delivery system.

FAQs

Can griseofulvin microsize be formulated as an oral suspension?

Yes. The principal challenges are particle settling, redispersibility, dose uniformity, taste and long-term physical stability. A successful product would require controlled particle engineering and a validated dosing device.

Is griseofulvin microsize interchangeable with Gris-PEG?

No. Microsize and ultramicrosize griseofulvin are distinct formulation categories with different particle characteristics and labeled dosing. Substitution should follow product-specific FDA labeling and pharmacy requirements.

Which excipients are most important for griseofulvin bioavailability?

Wetting agents, surfactants, lipid excipients and particle-size-control technologies are the most relevant. Tablet disintegrants alone are unlikely to resolve the underlying low-solubility and food-effect issues.

Can a new griseofulvin product receive patent protection?

Yes, if the product has novel and non-obvious formulation, particle-engineering, manufacturing or performance characteristics. Broad claims covering conventional griseofulvin tablets are unlikely to provide strong protection.

Is biosimilar competition relevant to griseofulvin microsize?

No. Griseofulvin is a small-molecule drug, so the relevant competition is from generic drugs, not biosimilars. Generic entry typically proceeds through the ANDA framework.

References

1. National Library of Medicine. (n.d.). DailyMed: Griseofulvin microsize tablet labeling. U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/

2. U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.accessdata.fda.gov/scripts/cder/ob/

3. U.S. Food and Drug Administration. (2024). Approved drug products and regulatory exclusivity information. https://www.fda.gov/drugs

4. U.S. Pharmacopeial Convention. (2024). United States Pharmacopeia and National Formulary. Rockville, MD: U.S. Pharmacopeial Convention.

5. U.S. Food and Drug Administration. (2023). Guidance for industry: Bioavailability and bioequivalence studies submitted in NDAs or INDs: General considerations. https://www.fda.gov/regulatory-information/search-fda-guidance-documents.